[TowerTalk] Antenna Modeling

[Jim W7RY]

I can attest to how difficult it is too!

I really struggled with my 80-40 fan inverted vee. Secret was to get the 
wires far apart, (not really in fan style), but that helped the 
interactions.

If your going to use a close spaced, each band wire close to the other, 
better model!

I would much rather have a resonate antenna than non, I believe that the 
efficiency is much better with something that is resonate. Unless you can 
feed it with open wire line all the way.


Thanks
73
Jim W7RY


-----Original Message----- 
From: Grant Saviers
Sent: Wednesday, July 11, 2018 4:45 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Antenna Modeling

For some good advice on modeling fans see
https://ac6la.com/aecollection4.html

Also, they are sensitive to height above ground so modeling at the
installed geometry is advised.   Using the modeling technique developed
by Cebik that AC6LA describes has yielded good results for me.
Otherwise there can be interactions that lead to a lot of cut and try
frustration.

Grant KZ1W

On 7/11/2018 12:12 PM, Jim Brown wrote:
> On 7/11/2018 10:52 AM, Bruce Jungwirth wrote:
>> I’m looking for someone in or around St Paul Mn that is fluent in EZNEC.
>
> A principal value of EZNEC and other modeling software is as a teaching 
> tool, and you only learn from it when YOU do it. It's not all that 
> difficult to learn once you get over the fear factor. The free version 
> that comes with the ARRL Antenna Book will model simple antennas like 
> you're thinking about.
>
> Here are several studies I've done to help think about problems like 
> yours.
>
> http://k9yc.com/VertOrHorizontal-Slides.pdf
>
> http://k9yc.com/VerticalHeight.pdf
>
> http://k9yc.com/43FtVertical.pdf
>
> http://k9yc.com/AntennaPlanning.pdf
>
> I am a big fan of fan dipoles. A good rule is to not try to put more than 
> three elements in the fan.  80/40 makes a good fan, so does 20/15/10. 
> Although I haven't done it, i suspect that 30/17 would too.
>
> 73, Jim K9YC
>
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